A fan impeller featuring a jet effect is described in German Published Patent Appln. No. 10 2007 009 366.
From German Published Patent Appln. No. 10 2005 031 197, a fan is described in which the incoming flow is shifted to a surface that is inclined by 30°.
Described in German Published Patent Appln. No. 10 2007 008 658 as the most proximate related art is a gear unit in which a fan impeller on a shaft is connected to the shaft in a torsionally fixed manner, and the fan hood includes a side wall that has an opening to allow air to enter.
A gear unit housing is described in British Published Patent Appln. No. 2 282 206, where a fan impeller is connected to a shaft, and a fan hood includes a sheet-metal part that extends radially toward the inside and is provided with an opening.
Japanese Laid-Open Application No. 8 105 521, on the other hand, describes connecting a fan impeller to a shaft in a torsionally fixed manner, the fan hood having a side wall that extends radially toward the inside and has an opening.
An air-cooled gear unit is also described in Japanese Laid-Open Application No. 10 061 754.
A fan impeller is described in U.S. Pat. No. 5,755,555.